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Ten Years On...


Matticus

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So, a decade on from building my first wooden track, I'm finally in a position to make my next.

 

The last one met a sorry end. The relationship I was in ended and I couldn't take it with me, so it ended up in hard rubbish. I salvaged the electrical bits out of it, but the track itself ceased to be many years ago. Sadly, I don't even have any images of it. C'est la vie.

 

Anyway, despite the fact my now wife (far more reasonable and tolerant than the ex-girlfriend) and I are expecting our first child in March, live in a two bedroom apartment on the top floor, I'm away 25-plus weekends a year with work, and we're looking to move in May, I couldn't help myself.

 

Having spoken about it for years, my mother in law gave me a router for Christmas. Shortly after New Year I had a very small wooden track. I made it for HO but found that didn't work, but 1:32 did. And instantly the need to build something bigger returned.

 

So, I've acquired two 1200x900 shots of 16mm MDF and routed them. I only went 5mm down, which I know isn't enough, but it works and that's all I care about for now.

 

The boards are joined lengthwise in a rough horseshoe design with a kink one one side. It's a single lane since I know nobody in my area that races, and am not home enough to warrant anything more.

 

I routed the track over the weekend, breaking three router bits in the process, and then painted an undercoat of white acrylic. Four layers, in fact.

 

Then I masked it off and painted the green that will form the base layer for the grass, which will go on later. I worked it so the slot effectively follows what would be the racing line.

 

Next I need to paint the track itself. I'm going with a black acrylic here, and will then dry brush some texture onto it. Using the small track I made a couple weeks back as a test bed, that netted the best results.

 

However, there are two problems I'm facing. The first is how to mask off the corners so they're round, and the second is how I paint the lines at the side of the track.

 

Going freehand isn't neat enough for mine, and a paint pen wouldn't give me the ability to weather the line the way I really want to. The only way I can think of doing it is to get some 3mm automotive tape and masking with that, with the usual masking tape behind it to protect the rest of the board.

 

I'm planning to get stuck into painting the track surface on the weekend, once I've had a chance to get out and buy some of the 3mm tape.

 

Actually laying the copper tape is still a fair way off; there's some more decoration I want to do to the grass first - my wife is from an artistic family so she's given me a few tips and ideas to give it a some more depth and interest, rather than being a flat green patch on the board like it was going to be.

 

Power wise, I've picked up a 30v variable power supply which should suit nicely. I think I'll run at 12v or 15v depending on the car.

 

The plan is to tap each rail at the edge of the board, and then run that back to the power supply. The hope is it'll give me some good, clean power.

 

The other thing I need to do is rig up a couple of latches to pull the two boards together when in use. That should be sufficient for alignment as I've three horses it rests on.

 

20180108_003324.jpg

Beauty.

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Welcome back to the fold...

 

 

Great start on your track too.

Well done.

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For masking the corners I have previously printed off the radius as a line on heavy paper or light card, cut around that radius and then used temporary spray adhesive to stick to track.

 

Alternatively if you have some scrap 3mm MDF lying around you could cut the curve as you like, tape up the corner and then use the MDF as a template to overlay and cut the tape

 

I think you will run at 12v (up to 18k motor) or 9v (for larger motor) on this track, 15v will be way overpowered but anyway you'll work it out.

 

You might think about framing the MDF underneath to keep it from warping, if so then it would be easy to bolt together with large heavy duty washers each side so that it doesn't dig into the framing.

 

For posting large images go to the source image location, right click on the image and choose "copy image address" then back here click on the image button in the text editor and paste your image link.

 

Good luck with the build, look forward to seeing the progress.

 

20180108_003324.jpg

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Thanks Ze.

 

The only issue is none of my corners have a standard radius. I routed using a nailed down garden hose, so there's wobbles and the radius varies. I designed the track freehand too, so while they might look fairly standard, not one of them is the same. Even the sweeper up the far end has probably three different radius measurements!

 

I think I'll have to suck up the 3mm tape process and deal with it. I can't see another way around it; the printed card process needs a printer. Despite working from home, I don't have one of them - I seldomly need a hard copy of anything these days.

Beauty.

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This weekend I finally got a chance to spend a bit more time on the track.

 

I finished painting the green, three coats in total, and then painted the track surface itself; two coats of black.

 

Once that was done, I sponged a grey wash over the track surface. Following that I masked sections of track off, mixed a darker tarmac, and reasonably heavily dry brushed those sections.

 

Again allowed to dry, I masked the remaining track, mixed a lighter colour grey and dry brushed those.

 

The finishing tough was painting a few patches in, which are almost black.

 

Copper tape was then laid, the track wired up to the power supply and run at 12v. There were some connection issues initially but I resolved those by laying copper tape over the joins in the wood. That's not a permanent solution, the plan is to wire it up underneath far more neatly than it currently is, but for testing purposes it does the job.

 

On the whole it's good. Surprisingly technical, with the last penultimate corner a real prick to get right; it makes or breaks your lap twice, because it sets up your run to begin the next as well, so if you get it wrong you pay for it over two laps.

 

The rough timing I've done suggests it's about 5.6s/lap. One mistake and that easily blows out to 8s. There's a fine balance between sliding nicely through the corners or getting too sideways. Similarly not carrying enough speed is also heavily punshied; the car doesn't struggle or get stuck, but the lack of momentum hurts.

 

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20180114_202309.jpg

 

20180114_205210.jpg

 

Next job is to add some texture to the grass, but need to bank a few laps first to understand where the car slides.

Edited by MatCoch
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That's coming along nicely...

Looking forward to where you go from here.

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Over the weekend I managed to spend a bit more time on it; this time sorting out the electrical side of things so it's a little more robust. Previously it had wires danging freely, so it worked but it was hardly 'finished'.

 

Both boards are now wired independently of one another. A Y-cable brings both halves together, connecting them to the power supply. There are taps at every crossing of the board, so eight in total, which is absolute overkill for such a small track, but I can, so I did.

 

The taps were done by drilling a hole through the board under the tape, then laying copper tape down the hole and feeding a wire up. They then run along the underside of the board to a termination point, which is hooked up to an XT60 connector. It's the same on both boards, with all the fun stuff happening at the other end of the Y-cable.

 

There's still some work to be done on the controller hookup. I've a Slot.it controller at my parents place in Adelaide that I'll eventually get back and hook up something more permanent. For the moment I'm using an old AFX controller with wires jammed in and electrical taped in place. It's not elegant, but it works and for the moment I don't have another option.

 

One unexpected problem was once I'd run the cables there was a huge voltage drop. Running 9v from the power supply, the track was only getting 0.3v. The problem was tracked down to poor connection between the wire and copper tape, which confused me for a while since it was hooked up the same way I've made every other track I've made. The solution mentioned above did the job, and a drop of solder in there should sort it out long term as well; and perhaps a dab of hot glue underneath just to give it a little more resilience.

 

I've been experimenting with track timing too, using Ultimate Racer and the webcam trigger option. It's not 100% reliable but there are things which can be done to sort that. Fortunately I had an old laptop kicking around so have rigged that up above the back straight, configured the start line, pit entry and exit, and am now just working through fine tuning the trigger points. The biggest problem is dropped laps, which it most likely do to lighting and a small trigger area. The other issue is the pit entry would trigger but not pit exit, so the car would gain fuel on the following lap, making any fuel race rather pointless. Again, there are things that can be done here, like making the pit exit far more sensitive, larger, etc etc.

 

Driving it, someone mentioned it's a technical little track, and it really, really is. You can lose shedloads of time at every corner, but it's the left hand hairpin in the infield which typically catches you out; too fast in and you lose all momentum and get stuck in the slot for a second. The last corner is a real sucker corner too; you've got to go fast through the left hander, but too fast and you slide too much through the right and don't get the run down the front straight. The trick is to get the back of the car out on the approach and then essentially Scandinavian flick it around the hairpin, then try not to get too greedy on the throttle as you accelerate onto the front straight as you then kill your run as the backend hangs out at some obtuse angle. Looks good, but it costs you 0.1s

 

On the whole though it's coming along. Once the wiring is finished I'll start on adding some texture to the grass. I'm toying with the idea of using flock and static grass, but given this is technically a temporary setup it's hard to justify the investment.

 

Hopefully all that will be done in the next couple weeks; once March hits my work really starts up again and I'm away more than I'm home. And with a baby due in late March the track will take a back seat for a while.

Beauty.

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  • 2 weeks later...

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